The objective of the proposed project is to investigate the potential of the gasotransmitter carbon monoxide (CO) as a neuroprotective agent in acute ischemic stroke (AIS) using a novel oral formulation of CO (HBI-002). Numerous studies, both in vitro and in vivo, demonstrate that CO has cytoprotective properties through anti- oxidant, anti-inflammatory and anti-apoptotic processes. In five studies in three independent laboratories, researchers found that the heme-oxygenase (HO)-1/CO pathway provides neuroprotection in animal models of AIS. In four of these studies exogenous administration of CO, which has been shown to up-regulate HO-1, reduced cerebral infarct size, improved behavioral scores and increased blood flow to the infarct border zone in experimental stroke. These independent studies provide compelling support for a potential beneficial role for the use of CO in the treatment of AIS. However, CO administration strategies have been limited to inhalation and intravenous approaches that carry inherent risks of safety and toxicity. HBI-002, an aqueous carboxylipid-protein liquid formulation, is being developed for the treatment of AIS. The administration of a defined dose of CO delivered by oral administration of HBI-002 obviates the problems associated with previously studied inhaled or intravenously administered carrier-metal CO. HBI-002 comprises a water-based solution containing CO. Proof of concept manufacture of HBI-002 has been demonstrated. Pharmacokinetic and pharmacodynamic studies in rats and in two adult healthy volunteers have demonstrated proof of concept feasibility, tolerability, and bioavailability. The next step in development is to demonstrate that CO delivered via the oral administration of HBI-002 improves outcome in appropriate AIS animal models and to further understand the potential mechanisms of neuroprotection.